Question: Which river {is in} the Zanzibar Archipelago, that has a {tributary} on the [Athi-Galana-Sabaki River}?
Paraphrase: Which waterway {is within} the Zanzibar Archipelago, that contains a {tributary} on the [Athi-Galana-Sabaki Waterway}?
SPARQL (Wikidata): SELECT ?answer WHERE { wd:Q706541 wdt:P706 ?answer . ?answer wdt:P974 wd:Q1508817}
Answer: Indian Ocean